Ether/ester dispersants

ABSTRACT

A dispersant which is a phosphate ester of a polymer which contains at least one ether group and a poly(oxyalkylenecarbonyl) chain (POAC chain) derivable from two or more different hydroxycarboxyl acids or lactones thereof. Also disclosed is the use of the dispersants in paints and printing inks including millbases. The preferred dispersants are phosphate esters of an alkyl end-capped poly(oxyalkylenecarbonyl) chain alcohol where the POAC chain is derived from ε-caprolactone and δ-valerolactone and the alkyl group is derived from a monohydroxypolyalkyleneglycol.

The present invention relates to a compound for dispersing a particulatesolid in a liquid medium, its method of preparation and to compositionsand millbases containing said compound and a particulate solid,including paints and inks.

WO 97/19948 discloses a dispersant which is a phosphate ester of a blockcopolymer RO—(C₂H₄O)_(m)(PES)_(n)—OH wherein R is C₁₋₄-alkyl, PES is apolyester derived from a cyclic lactone such as valerolactone orε-caprolactone, m is from 5 to 60, n is from 2 to 30 and where themolecular weight of RO(C₂H₄O)_(m) is greater than the molecular weightof (PES)_(n). The dispersants are said to be particularly effective fordispersing particulate solids such as pigments in an aqueous medium.

It has now been found that dispersants exhibiting superior propertiessuch as solubility in the liquid medium can be obtained by using morethan one hydroxycarboxylic acid or lactone to make the polyester(PES)_(n).

According to the invention there is provided a dispersant which is aphosphate ester of a polymer which contains at least one ether group anda poly(oxyalkylenecarbonyl) chain derivable from two or more differenthydroxycarboxylic acids or lactones thereof including their salts. Thedispersant is hereinafter referred to as “Ether dispersant”. Preferably,the poly(oxyalkylenecarbonyl) chain is derivable from two differenthydroxy carboxylic acids or lactones thereof. The molecular weight ofthe polymer can vary between wide limits depending whether thedispersant is to be used for dispersing a particulate solid in a polarliquid medium including water or whether it is for use in asubstantially non-polar liquid medium. The molecular weight of thepolymer is typically from 200 to 10,000, preferably from 300 to 5,000and especially. from 400 to 2,000.

According to a preferred aspect of the invention, the dispersant is aphosphate ester of a copolymer of formula 1

RO(CO—A—O)_(n)(CO—B—O)_(m)H  (1)

including salts thereof wherein

R is a polymerisation terminating group containing at least one etherlink;.

A and B are each, independently, different alkenylene groups orC₁₋₁₇-alkylene groups optionally substituted by alkyl;

n and m are integers; and

n+m is from 2 to 200.

The copolymer of formula 1 may be a block or random polymer.

In the dispersant of formula 1, [(CO—A—O)_(n)(CO—B—O)_(m)] represents apolyoxyalkylenecarbonyl chain and the group RO may be attached to eitherof the oxyalkylenecarbonyl groups containing A and B. It is referred tohereinafter as a pplyoxyakylenecarbonyl chain or POAC chain. Thecopolymer of formula 1 containing the polymerisation terminating groupis referred to hereinafter as a TPOAC alcohol.

Where A and/or B is alkenylene it is preferably C₂₋₁₇-alkenylene andespecially C₁₅₋₁₇-alkenylene.

When the dispersant is for use in a non-polar medium, it is preferredthat at least one of A and B is C₈₋₁₇-alkylene and when the dispersantis for use in a polar liquid medium, including water, it is preferredthat one, or more preferably both, A and B are C₁₋₆-alkylene andespecially C₄₋₆-alkylene optionally substituted by alkyl.

The alkyl substituent in A and B may be linear or branched and ispreferably C₁₋₈-alkyl, more preferably C₁₋₆-alkyl and especiallyC₁₋₄-alkyl.

It is particularly preferred that the molecular weight of the ethermoiety RO is greater than that of the POAC chain.

The polymerisation terminating group R containing at least one ethergroup is preferably a residue of a mono-hydroxy glycol or a mono-hydroxypolyalkyleneglycol. Preferred glycols or polyalkyleneglycols are thosederivable from C₂₋₄alkyleneoxide, especially ethyleneoxide orpropyleneoxide, including mixtures thereof. When the dispersant is foruse in a polar liquid, including water, the glycol or polyalkyleneglycolis preferably derivable from ethylene oxide and when the dispersant isfor use in a non-polar liquid medium, the glycol or polyalkyleneglycolis preferably derivable from propyleneoxide. When the dispersant is foruse in a polar liquid medium, including water, it is particularlypreferred that the glycol or polyalkyleneglycol is derivable fromethylene oxide and that both A and B are different C₁₋₆-alkylene groups.

Examples of hydroxycarboxylic acids are 12-hydroxystearic, ricinoleic,12-hydroxydodecanoic, 5-hydroxydodecanoic, 5-hydroxydecanoic,4-hydroxydecanoic, glycolic, lactic, 6-hydroxyhexanoic and5-hydroxypentanoic acids.

Examples of lactones are propiolactone, butyrolactone, valerolactone(especially δ-valerolactone) and optionally alkyl-substitutedε-caprolactone. The alkyl substituent in ε-caprolactone may be linear orbranched and is preferably C₁₋₈-alkyl, more preferably C₁₋₆-alkyl andespecially C₁₋₄-alkyl. Examples of such groups are methyl and tertiarybutyl.

The alkyl-substituted ε-caprolactones are obtainable by oxidation ofalkyl-substituted cyclohexanone and consequently many are mixtures ofalkyl-substituted ε-caprolactone. Thus, the oxidation of 2-methylcyclohexanone often results in a mixture of 7-methyl (95%) and 3-methyl(5%) ε-caprolactone. However, the oxidation of 4-alkylcyclohexanoneresults only in the 5-alkyl ε-caprolactone. Other examples ofalkyl-substituted ε-caprolactone are 6-methyl; 4-methyl; 5-methyl;5-tertiary butyl; 4,6,6-trimethyl and 4,4,6-trimethyl derivatives.7-methyl ε-caprolactone is the preferred alkyl-substitutedε-caprolactone.

The polymerisation terminating group R is preferably derived from ahydroxy compound T—OH which is attached to the glycol orpolyalkyleneglycol by an ether linkage wherein T is C₁₋₃₅-hydrocarbylwhich is optionally substituted by halogen, tertiary amino, hydroxy,C₁₋₆-alkoxy, amine, ester or urethane groups.

When T contains amide, ester or urethane groups it preferably containstwo such groups and the group R is preferably a diester, diamide ordi-urethane containing at least one ether link. Groups represented by Rwhich contain either amide, ester or urethane groups are convenientlyprepared by reacting two fragments of T which contain a hydroxy or aminogroup with, for example, a dibasic acid or anhydride thereof or adi-isocyanate.

Examples of dibasic acids or anhydrides are terephthalic, phthalicanhydride, adipic acid, maleic acid and maleic anhydride.

Examples of di-isocyanates are toluene di-isocyanate and isophoronedi-isocyanate.

The group T may be aromatic, hetrocyclic, alicyclic or aliphatic whichmay be linear or branched, saturated or unsaturated. It is preferredthat T contains not greater than 20 carbon atoms and particularly notgreater than 10 carbon atoms. It is especially preferred that T isC₁₋₆-alkyl such as methyl.

Other examples of the group T are C₂H₅—, CH₃(CH₂)₉—, CH₃(CH₂)₁₁—,CH₃(CH₂)₁₅—, CH₃(CH₂)₁₇—, CH₃(CH₂)₂₉—, CH₃(CH₂)₇CH═CH(CH₂)₇—, CH₃OCH₂—,CH₃(CH₂)₄CH═CHCH₂CH═CH(CH₂)₇— the residue of abietyl alcohol, i.e.abietyl alcohol without the OH group, nonylphenol.

As noted hereinbefore, it is particularly preferred that T is C₁₋₆-alkyland also that R is derivable from ethylene oxide since such dispersantshave been found particularly effective in dispersing particulate solidsin a polar liquid medium, including water.

Examples of R containing at least one ether link are the residue oftripropyleneglycol monomethylether, dipropyleneglycol monomethylether,triethyleneglycol monomethylether, methoxypropyleneglycols andmethoxyethyleneglycols having a molecular weight between 250 and 750,ethoxylated C₉₋₁₁-fatty alcohol with a molecular weight of 270 andethoxylated nonylphenol having a molecular weight of 360.

The dispersant of Formula 1 is obtainable by polymerising two differenthydroxycarboxylic acids or lactones thereof in the presence of amonohydric alcohol R—OH to form a TPOAC alcohol having a terminalhydroxy group i.e. a POAC chain having a terminal hydroxy group and apolymerisation terminal group. The TPOAC alcohol is subsequently reactedwith a phosphating agent, especially P₂O₅ and polyphosphoric acid.

The TPOAC alcohol may be prepared by reacting the hydroxy carboxylicacids or lactones thereof together and then reacting the compound soformed containing the POAC chain with a polymerisation terminatingcompound. However, it is preferred to form the TPOAC alcohol directly byreacting the hydroxy carboxylic acids, or lactones thereof, in thepresence of a polymerisation terminating compound. The reaction ispreferably carried out in an inert atmosphere and optionally in thepresence of an inert solvent and esterification catalyst. The reactionis typically carried out between 150 and 180° C. It is also preferred tocarry out the reaction in the absence of an inert solvent.

Examples of suitable catalysts are tetra-alkyl titanate, for, example,tetrabutyltitanate, zinc salt of an organic acid such as zinc acetate,tin salts of organic acids such as dibutyl tin dilaurate, zirconium saltof an aliphatic alcohol such as zirconium isopropoxide, toluenesulphonicacid or a strong organic acid such as haloacetic acid and particularlytrifluoroacetic acid.

The dispersant which is a phosphate ester of Formula 1 is obtainable byreacting a TPOAC alcohol with a phosphating agent wherein the ratio ofthe alcohol to each phosphorus atom of the phosphating agent is from 3:1to 1:1 and especially from 2:1 to 1:1. It is especially preferred thatthe ratio of each TPOAC alcohol to each phosphorus atom of thephosphating agent is less than 2, for example, about 1.5:1 when thedispersant is a mixture of mono- and di-phosphate esters.

The reaction between the TPOAC alcohol and phosphating agent ispreferably carried out in an inert atmosphere such as nitrogen, underanhydrous conditions. The reaction may be carried out in an inertsolvent but it is more convenient to react the TPOAC alcohol with thephosphating agent in the absence of a solvent. The reaction temperatureis preferably above 60 and especially above 80° C. In order to avoidcharring the dispersant, the temperature is preferably less than 120 andespecially less than 100° C.

As a less preferred variant, the dispersant of Formula 1 may also beprepared by reacting a monohydric, alcohol with a preformed POAC acidand subsequently reacting the TPOAC alcohol with a phosphating reagent.

The dispersants may also contain additional ester, amide or amine saltgroups formed by reacting the dispersant with an alcohol oralkanolamine.

The dispersants may be in the form of a free acid or it may form a saltwith an alkali metal, ammonia, an amine, alkanolamine or quaternaryammonium salt depending whether the dispersant is to be used to dispersea particulate solid in a polar medium, including water, or in anon-polar medium. When the medium is a polar medium or water, thedispersant is preferably in the form of its free acid or in the form ofits alkali metal salt and when the medium is a non-polar medium thedispersant is preferably in the form of a salt with an amine. Examplesof suitable amines are n-butylamine, diethanolamine anddimethylaminopropylamine.

The TPOAC alcohols used in the preparation of the dispersants are novel.

Thus, according to the invention there is provided a TPOAC alcohol offormula RO[(CO—A—O)_(n)(CO—B—O)_(m)]H wherein R, A, B, n and m are asdefined hereinbefore.

As noted hereinbefore, the dispersants are particularly useful fordispersing a particulate solid in a liquid medium.

According to a further aspect of the invention there is provided acomposition comprising a particulate solid and an Ether Dispersant.

According to a still further aspect of the invention there is provided adispersion comprising an Ether Dispersant, a particulate solid and aliquid medium.

The solid present in the dispersion may be any inorganic or organicsolid material which is substantially insoluble in the liquid medium atthe temperature concerned and which it is desired to stabilise in afinely divided form therein.

Examples of suitable solids are pigments for solvent inks; pigments,extenders, fibres and fillers for paints and plastics materials; dyes,especially disperse dyes; optical brightening agents and textileauxiliaries for solvent dyebaths, inks and other solvent applicationsystems; solids for oil-based and invert-emulsion drilling muds; dirtand solid particles in dry cleaning fluids; particulate ceramicmaterials; magnetic materials and magnetic recording media, andbiocides, agrochemicals and pharmaceuticals which are applied asdispersions in organic media.

Examples of suitable plastics materials are synthetic resins such asthose used as sheet moulding compounds and bulk, moulding compoundswhich comprise unsaturated polyester resins containing reinforcingfibres and fillers.

A preferred solid is a pigment from any of the recognised classes ofpigments described, for example, in the Third Edition of the ColourIndex (1971). and subsequent revisions of, and supplements thereto,under the chapter headed “Pigments”. Examples of inorganic pigments aretitanium dioxide, zinc oxide, Prussian blue, cadmium sulphide, ironoxides, vermilion, ultramarine and the chrome pigments, includingchromates, molybdates and mixed chromates and sulphates of lead, zinc,barium, calcium and mixtures and modifications thereof which arecommercially available as greenish-yellow to red pigments under thenames primrose, lemon, middle, orange, scarlet and red chromes. Examplesof organic pigments are those from the azo, disazo, condensed azo,thioindigo, indanthrone, isoindanthrone, anthanthrone, anthraquinone,isodibenzanthrone, triphendioxazine, quinacridone and phthalocyanineseries, especially copper phthalocyanine and its nuclear halogenatedderivatives, and also lakes of acid, basic and mordant dyes. Carbonblack, although strictly inorganic, behaves more like an organic pigmentin its dispersing properties. Preferred organic pigments arephthalocyanines, especially copper phthalocyanines, monoazos, disazos,indanthrones, anthranthrones, quinacridones and carbon blacks.

Other preferred solids are: extenders and fillers such as talc, kaolin,silica, barytes and chalk; particulate ceramic materials such asalumina, silica, zirconia, titania, silicon nitride, boron nitride,silicon carbide, boron carbide, mixed silicon-aluminium nitrides andmetal titanates; fire retardant fillers such as aluminium hydroxide andmagnesium hydroxide; particulate magnetic materials such as the magneticoxides of transition metals, especially iron and chromium, e.g.gamma-Fe₂O₃, Fe₃O₄, and cobalt-doped iron oxides, calcium oxide,ferrites, especially barium ferrites; and metal particles, especiallymetallic iron, nickel, cobalt and alloys thereof; and agrochemicals suchas the fungicides flutriafen, carbendazim, chlorothalonil and mancozeb.

The liquid medium present in the dispersions of the invention ispreferably a polar organic liquid or a substantially non-polar organicliquid or halogenated hydrocarbon. By the term “polar” in relation tothe organic medium is meant an organic liquid or resin capable offorming moderate to strong bonds as described in the article entitled “AThree Dimensional Approach to Solubility” by Crowley et al in Journal ofPaint Technology, Vol. 38, 1966, at page 269. Such organic mediagenerally have a hydrogen bonding number of 5 or more as defined in theabove mentioned article.

Examples of suitable polar organic liquids are amines, ethers,especially lower alkyl ethers, organic acids, esters, ketones, glycols,alcohols and amides. Numerous specific examples of such moderatelystrongly hydrogen bonding liquids are given in the book entitled“Compatibility and Solubility” by Ibert Mellan (published in 1968 byNoyes Development Corporation) in Table 2.14 on pages 39-40 and theseliquids all fall within the scope of the term polar organic liquid asused herein.

Preferred polar organic liquids are dialkyl ketones, alkyl esters ofalkane carboxylic acids and alkanols, especially such liquids containingup to, and including, a total of 6 carbon atoms. As examples of thepreferred and especially preferred liquids there may be mentioneddialkyl and cycloalkyl ketones, such as acetone, methyl ethyl ketone,diethyl ketone, di-isopropyl ketone, methyl isobutyl ketone, di-isobutylketone, methyl isoamyl ketone, methyl n-amyl ketone and cyclohexanone;alkyl esters such as methyl acetate, ethyl acetate, isopropyl acetate,butyl acetate, ethyl formate, methyl propionate, methoxy propylacetateand ethyl butyrate; glycols and glycol esters and ethers, such asethylene glycol, 2-ethoxyethanol, 3-methoxypropylpropanol,3-ethoxypropylpropanol, 2-butoxyethyl acetate, 3-methoxypropyl acetate,3-ethoxypropyl. acetate and 2-ethoxyethyl acetate; alkanols such asmethanol, ethanol, n-propanol, isopropanol, n-butanol and isobutanol anddialkyl and cyclic ethers such as diethyl ether and tetrahydrofuran.

The substantially non-polar, organic liquids which may be used, eitheralone or in admixture with the aforementioned polar solvents, are forexample, aromatic hydrocarbons, such as toluene and xylene, aliphatichydrocarbon such as pentane, heptane, octane and halogenated aliphaticand aromatic hydrocarbons, such as trichloroethylene, perchloroethyleneand chlorobenzene. The non-polar organic liquid may also be acommercially available mixture such as an aliphatic or aromaticdistillate, for example, white spirits.

The liquid medium may also be water or a mixture of water with a polarorganic liquid, substantially non-polar organic liquid or halogenatedhydrocarbon. When the liquid medium contains water, the amount of wateris preferably less than 5% by weight of the liquid medium.

When the liquid medium is water it is preferred that the molecularweight of the polyester represented by (CO—A—O)_(n)(CO—B—O)_(m) informula 1 is less than or equal to the molecular weight of the polyethermoiety represented by the group RO—.

Preferably, the liquid medium is a polar organic liquid.

Examples of suitable polar resins, as the medium for the dispersion formof the present invention, are film-forming resins such as are/suitablefor the preparation of inks, paints and chips for use in variousapplications such as paints and inks. Examples of such resins includepolyamides, such as Versamid™ and Wolfamid™, and cellulose ethers, suchas ethyl cellulose and ethyl hydroxyethyl cellulose. Examples of paintresins include short oil alkyd/melamine-formaldehyde,polyester/melamine-formaldehyde, thermosettingacrylic/melamine-formaldehyde, long oil alkyd and multi-media resinssuch as acrylic and urea/aldehyde.

If desired, the dispersions may contain other ingredients, for exampleresins (where these do not already constitute the organic medium),binders, fluidising agents (such as those described in GB-A-1508576 andGB-A-2108143), anti-sedimentation agents, plasticisers, levelling agentsand preservatives.

The dispersions typically contain from 5 to 95% by weight of the solid,the precise quantity depending on the nature of the solid and thequantity depending on the nature of the solid and the relative densitiesof the solid and the liquid medium. For example, a dispersion in whichthe solid is an organic material, such as an organic pigment, preferablycontains from 15 to 60% by weight of the solid whereas a dispersion inwhich the solid is an inorganic material, such as an inorganic pigment,filler or extender, preferably contains from 40 to 90% by weight of thesolid based on the total weight of dispersion.

The dispersion may be obtained by any of the conventional methods knownfor preparing dispersions. Thus, the solid, the liquid medium and thedispersant may be mixed in any order, the mixture then being subjectedto a mechanical treatment to reduce the particles of the solid to anappropriate size, for example by ball milling, bead milling, gravelmilling or plastic milling until the dispersion is formed.Alternatively, the solid may be treated to reduce its particle sizeindependently or in admixture with either the liquid medium or thedispersant, the other ingredient or ingredients then being added and themixture being agitated to provide the dispersion.

If the composition is required in dry form, the liquid medium ispreferably volatile so that it may be readily removed from theparticulate solid by a simple separation means such as evaporation. Itis preferred, however, that the dispersion comprises the liquid medium.

If the dry composition consists essentially of the dispersant and theparticulate solid, it preferably contains at least 0.2%, more preferablyat least 0.5% and especially at least 1.0% dispersant based on weight ofthe particulate solid. Preferably the dry composition contains notgreater than 100%, preferably not greater than 50%, more preferably notgreater than 20% and especially not greater than 10% by weight based onthe weight of the particulate solid.

As described hereinbefore, the dispersants of the invention areparticularly suitable for preparing mill-bases where the particulatesolid is milled in a liquid medium in the presence of both a particulatesolid and a film-forming resin binder.

Thus, according to a still further aspect of the invention there isprovided a mill-base comprising a particulate solid, dispersant, liquidmedium and a film-forming resin.

Typically, the mill-base contains from 20 to 70% by weight particulatesolid based on the total weight of the mill-base. Preferably, theparticulate solid is not less than 30, and especially not less than 50%by weight of the mill-base.

The amount of resin in the mill-base can vary over wide limits but ispreferably not less than 10%, and especially not less than 20% by weightof the continuous/liquid phase of the mill-base. Preferably, the amountof resin is not greater than 50% and especially not greater than 40% byweight of the continuous/liquid phase of the mill-base.

The amount of dispersant in the mill-base is dependent on the amount ofparticulate solid but is preferably from 0.5 to 5% by weight of themill-base.

Dispersions and mill bases containing the dispersants of the inventionare particularly suitable for use in paints, especially high solidspaints, inks, especially flexographic, gravure and screen inks, andnon-aqueous ceramic processes, especially tape-coating, doctor-blade,extrusion and injection moulding type processes.

The dispersants of the present invention exhibit advantage over knowndispersants which contain a POAC chain derived from a singlehydroxycarboxylic acid or lactone. In particular, they exhibit superiorsolubility in liquid media such as solvents and do not separate orcrystallise when stored at 4° C. for lengthy periods. When stored at lowtemperatures, separation can occur at −240° C. but the dispersantsreadily re-dissolve on warming to 4-10° C. When incorporated into paintsand painting inks, the dispersants of the present invention give rise tohigher gloss readings and lower haze values in the resultant paints andinks.

The invention is further illustrated by the following examples whereinall references to amounts are in parts by weight unless indicated to thecontrary.

EXAMPLES

Preparation of Alkyl ε-caprolactone Intermediates

Lactone 1

4 and 6-methyl ε-caprolactone

3-methylcyclohexanone (10 parts, 0.089M ex. Aldrich) was dissolved indichloromethane (400 ml) and sodium bicarbonate (37 parts) added,portionwise, with vigorous stirring at 18-20° C. under a nitrogenatmosphere. A suspension of 3-chloroperoxybenzoic acid (24.17 parts,0.098M ex. Fluka) in dichloromethane (100 ml) was then added over 10minutes with external cooling to maintain a temperature below 20° C. andthe reaction continued at 18-20° C. by stirring ,for a further 4 hours.The reaction mix was then shaken with a 10% aqueous solution of sodiumsulphite (2×250 ml) followed by water (2×250 ml) and then dried overanhydrous magnesium sulphate. After evaporating the solvent a mixture of4- and 6-methyl, ε-caprolactone was obtained as a thin yellow oil (8parts).

Lactone 2

3- and 7-methyl ε-caprolactone

This was prepared in the same manner as that described for Lactone 1except using the same weight of 2-methylcyclohexanone (ex. Aldrich) inplace of 3-methylcyclohexanone. The product was obtained as a clear oil(8 parts) and is mainly 7-methyl ε-caprolactone (95%).

Lactone 3

5-methyl ε-caprolactone

This was prepared in similar manner to Lactone 1 except using 4-methylcyclohexanone (50 parts; 0.445 m ex. Aldrich) in place of the3-methylcyclohexanone with appropriate increase in the dichloromethane(1500 ml), sodium bicarbonate (8.1 parts, 1.0M) and3-chloroperoxybenzoic acid (123 parts, 0.5M). The reaction temperaturewas maintained below 10° C. throughout. The 5-methyl ε-caprolactone wasobtained as a clear yellow oil (49 parts).

Lactone 4

5-tertbutyl ε-caprolactone

This was prepared in the same manner as Lactone 1 except using 4-tertbutylcyclohexanone (10 parts, 0.065 m ex. Aldrich),3-chloroperoxybenzoic acid (17.5 parts, 0.0713M), sodium bicarbonate(11.5 parts, 0.143M) and dichloromethane (750 ml) in place of the3-methyl cyclohexanone and amounts described for Lactone 1. The productwas obtained as an oil (10.2 parts).

Lactone 5

4,6,6- and 4,4,6-trimethyl ε-caprolactone

3,3,5-Trimethylcyclohexanone (10 parts, 0.071M ex. Fluka) was dissolvedin dichloromethane (200 ml). 3-chloroperoxybenzoic acid (30.6 parts,0.142M) was added, portionwise, with stirring and the reaction mixcooled externally below 5° C. Trifluoroacetic acid (8 parts, 0.071M ex.Fluka) was added dropwise over 30 minutes with stirring at 0-5° C. andthe reactants stirred for a further 20 hours allowing the temperature torise to 18-20° C.

The reaction mass was then poured into a 10% w/w aqueous solution ofsodium sulphite (50 ml) and allowed to stand. The solvent layer wasseparated and shaken with 10% aqueous sodium sulphite (2×50 ml), 10% w/waqueous potassium carbonate (3×50 ml) and water (2×50 ml). Finally, thesolvent phase was dried over anhydrous sodium sulphate and the solventevaporated. The product was obtained as a clear colourless oil (11parts).

Examples of Dispersants

In the following examples, the composition of the polymerisationterminating group containing at least one ether link indicates theresidue of T—OH (e.g. Me or Et followed by the polyalkyleneoxide (e.g.PEG for polyethyleneglycol). The components of the attached POAC chainare indicated (e.g. δ-val, ε-cap, etc. for δ-valerolactone andε-caprolactone). The figures in parentheses indicate the molar ratio ofthe ether containing polymerisation group to lactone(s). The ratio ofthe TPOAC alcohol to phosphorus atom of the phosphating agent isindicated at the end of the descriptor.

Example 1 EtO PEG 3 (1) ε-cap (1.45) δ-val (1.45) phosphate (2:1phosphorus atom)

Triethyleneglycolmonoethyl ether (EtO PEG3; 25 parts, 0.14M ex Fluka),ε-caprolactone (23.21 parts, 0.203M ex Aldrich) and δ-valerolactone(20.36 parts, 0.203 ex Fluka) were stirred at 130° C. under nitrogen.Zirconium butylate (0.4 parts) was added and the reactants heated to175° C. and stirred at this temperature for 6 hours. After the reactantsstirred at 80° C. for 6 hours. On cooling, the product was obtained as abrown viscous liquid (80 parts). This is Dispersant 1.

Comparative Example A EtO PEG 3 (1) ε-cap (2.9) phosphate (2:1phosphorus atom)

This was prepared in an identical manner to Dispersant 1 in Example 1except using ε-caprolactone (46.41 parts) as the sole lactone and using0.10 parts zirconium butylate and 23.85 parts polyphosphoric acidinstead of the amounts described in Example 1. On cooling, the productwas obtained as a brown wax (82 parts). This is Dispersant A.

Example 2 MeO PEG 750 (1) δ-val (4) 7-Me ε-cap (3.5) (2:1 phosphorusatom)

Polyethyleneglycolmonomethyl ether (MW 750, 25 parts, 0.033M ex Fluka),δ-valerolactone (13.35 parts, 0.133M) and 7-methyl-ε-caprolactone (14.95parts, 0.1166M ex Lactone 2) were stirred under nitrogen at 130° C.Zirconium butylate (0.3 parts) were added and the reactants stirredunder nitrogen for 6 hours at 175° C. After cooling to 80° C.,polyphosphoric acid (5.78 parts, 0.0407M) was added and the reactantsstirred at 80° C. for 6 hours. After cooling, the product, Dispersant 2,was obtained a brown, viscous liquid (45 parts).

Comparative Example B MeO PEG 750 (1) δ-val (7.5) phosphate (2:1phosphorus atom)

This was prepared in an identical manner to Dispersant 2 of Example 2except using 35 parts of the glycol, 35.04 parts δ-valerolactone, 0.2parts zirconium butylate and 7.86 parts polyphosphoric acid. The productwas obtained as a brown viscous liquid which on cooling gave a brown wax(71 parts). This is Dispersant B.

Example 3 MeO PEG 750 (1) ε-cap (4.5) δ-val (2.5) (2:1 phosphorus atom)

This was also prepared in analogous manner to Dispersant 2 of Example 2except using MeO PEG 750 (30 parts, 0.04 mole), ε-caprolactone (20.54parts, 0.18 mole) and δ-valerolactone (10.01 parts, 0.1 mole) in placeof the amounts used in Example 2. Phosphation was carried out using 6.66parts (0.047 moles) polyphosphoric acid. The product was obtained as abrown viscous liquid (60 parts). This is Dispersant 3.

Examples 4 to 6 and Comparative Examples C and D

The dispersants (2 parts) were dissolved in a 4:1. mixture ofmethoxypropylacetate and n-butanol (10 ml) by heating is necessary. Theappearance of the solution was examined visually at 200° C., after 3days at 4° C., after 2 days at −10° C. and after 2 days storage at −10°C. and allowing to warm to 20° C. The results are given in Table 1below.

TABLE 1 Appearance of Solution After After 2 After 2 days at At 3 daysdays at −10° C. and Example Dispersant 20° C. at 4° C. −10° C. warmingto 20° C. 4 1 Clear Clear Clear Clear 5 2 Clear Clear Crystals Clear 6 3Clear Clear Crystals Clear C A Clear Crystals Crystals Slight cloudylayer D B Clear Crystals Crystals Clear

Example 7 MeO PEG 2000 (1) ε-cap (4) δ-val (3) (1.5:1 phosphorus atom)

Polyethyleneglycolmonomethylether MW 2000 (50 parts, 0.025M ex Fluka),ε-caprolactone (11.41 parts, 0.1M ex Aldrich) and δ-valerolactone (7.51parts, 0.075M) were stirred under nitrogen at 140° C. Zirconium butylate(0.3 parts) was added and the reactants stirred under nitrogen for 6hours. After cooling to 90° C., polyphosphoric acid (2.85 parts) wasadded and the reactants were stirred at 90-95° C. for 6 hours. A brownviscous liquid was obtained giving a yellow-brown wax on cooling (65parts). This is Dispersant 4.

Comparative Example C MeO PEG 2000 (1) ε-cap (7) (1.5:1 phosphorus atom)

This was prepared in identical manner to Dispersant 4 of Example 7except using 19.97 parts ε-caprolactone as the sole lactone. Theproduct, Dispersant C, was obtained as a pale yellow viscous oil (65parts) which formed a white gel on cooling.

Dispersant 4 and Dispersant C (3 parts) were each dissolved in water (7parts) by heating. After cooling to 20° C., Dispersant 4 gave a clearaqueous solution, and Dispersant C gave a white gel.

Examples 8 to 18

The Ether Dispersants listed in Table 2 below were made in similarmanner to Dispersant 1 described in Example 1 except using the startingmaterials and amounts as indicated in Table 2. The components used. tomake the alkyl end-capped polyoxyalkylene chain alcohol (TPOAC alcohol)is as given in Table 2 where the molar amounts are given in parenthesesfollowing the components. The ratio of TPOAC alcohol to each phosphorusatom of the phosphating agent (P₂O₅) is listed as “phosphorus ratio”.The figures following PEG and PPG indicate the number-average molecularweight of the polyalkyleneglycolmonoalkylether.

TABLE 2 Example Dispersant TPOAC alcohol Phosphorus ratio 8 5 MeO PEG550 (1), ε-cap (2), 5-Me-ε-cap (2) 3:1 9 6 MeO PEG 750 (1), ε-cap (2),δ-val (2) 3:1 10 7 MeO PEG 750 (1), ε-cap (2), 7-Me-ε-cap (2) 3:1 11 8MeO PEG 750 (1), ε-cap (4), δ-val (2) 3:1 12 9 MeO PEG 750 (1), ε-cap(4), 7-Me-ε-cap (2) 3:1 13 10 MeO PEG 350 (1), ε-cap (2), 7-Me-ε-cap (1)3:1 14 11 MeO PEG 350 (1), ε-cap (2), δ-val (1) 3:1 15 12 MeO PEG 550(1), ε-cap (2), δ-val (2) 3:1 16 13 MeO PEG 350 (1), ε-cap (14), δ-val(9) 3:1 17 14 MeO PEG 750 (1), ε-cap (30), δ-val (16) 3:1 18 15 MeO PEG206 (1), ε-cap (3.2), 4-Me-ε-cap (2) 2:1 Footnote to Table 2 MeO PEG 550is polyethyleneglycolmonomethylether of MW 550 ex Fluka MeO PEG 750 ispolyethyleneglycolmonomethylether of MW 750 ex Fluka MeO PEG 350 ispolyethyleneglycolmonomethylether of MW 350 ex Fluka MeO PPG 206 istripropyleneglycolmonomethylether of MW 206 ex Aldrich ε-cap isε-caprolactone ex Aldrich δ-val is δ-valerolactone ex Fluka 5-Me-ε-capis Lactone 3 7-Me-ε-cap is Lactone 2 4-Me-ε-cap is Lactone 1

Comparative Examples D to I

The comparative dispersants listed in Table 3 below were made in similarmanner to Dispersant 1 described in Example 1 except using thepolyalkyleneglycol mono alkyether indicated in the column headed TPOACalcohol. The figures in parentheses indicate the molar amounts ofpolyalkyleneglycolmonoalkylether and ε-caprolactone. Again, the ratio ofTPOAC alcohol to each phosphorus atom of the phosphating agent (P₂O₅) islisted as “phosphorus ratio” and the figures following PEG and PPGindicate the number-average molecular weight of thepolyalkyleneglycolmonoalkylether; Dispersants I and G are equivalent toExamples 20 and 8, respectively, of U.S. Pat. No. 5,130,463.

TABLE 3 Comparative Dispersant TPOAC alcohol Phosphorus ratio D MeO PEG164 (1) ε-cap (3) 3:1 E MeO PPG 206 (1) ε-cap (2.7) 3:1 F EtO PEG 178(1) ε-cap (2.9) 3:1 G MeO PPG 206 (1) ε-cap (5.2) 2:1 H MeO PEG 750 (1)ε-cap (46) 3:1 I MeO PEG 350 (1) ε-cap (23.2) 3:1 Footnote to Table 3MeO PEG 164 is polyethyleneglycolmonomethylether of MW 164 MeO PPG 206is polypropyleneglycolmonomethylether of MW 206 EtO PEG 178 ispolyethyleneglycolmonoethylether of MW 178 MeO PEG 750, MeO PEG 350 andε-cap are as explained in the footnote to Table 2.

Examples 18 to 28 and Comparative Examples J to O

The dispersants (2 parts) were dissolved in a 4:1 mixture ofmethoxypropylacetate/n-butanol (10 parts) with heating as necessary. Thesolutions so obtained were examined after standing for 16 hours at 20°C., after storing for 2 days at,4° C., after storing for 2 days at −10°C. and after storage for 2 days at −10° C. and allowing to return to 20°C. over a 6 hour period. The results are given in Table 4 below. Theseexamples show that the Dispersants according to the invention exhibitsuperior solubility and superior stability to analogous dispersantswhere the TPOAC alcohol is derived from ε-caprolactone as the solelactone.

TABLE 4 Storage 16 Exam- Disper- hours at 2 days 2 days at 2 days at−10° C. then ple sant 20° C. at 4° C. −10° C. 6 hours at 20° C. 18 5 CLCL H CL 19 6 CL CL CR CL 20 7 CL CL CR CL 21 8 CL CL CR CL 22 9 CL CL CRCL 23 10 CL CL CL CL 24 11 CL CL H CL 25 12 CL CL CR CL 26 13 H few CRCR H 27 14 CL CL CR CL 28 15 CL CL CR CL J D few CR CR CR CR K E few CRCR CR CR L F sl H CR CR CR M H few CR CR CR CR N I CL CR CR CR O G CL CRCR CR Footnote to Table 4 CL is clear, H is hazy, CR is crystals and slis slight

Examples 29 to 42 and Comparative Examples P to W

The Dispersant (0.2 part) was dissolved in a 4:1 mixture ofmethoxypropylacetate/n-butanol (2.3 parts) in a glass vial with warmingas necessary. Glass beads (3 mm, 17 parts) were added together withtitanium dioxide white pigment (7.5 parts Tioxide TR92 ex Tioxide). Thevial was then sealed and the pigment milled on a horizontal shaker for16 hours. The fluidity of the resultant dispersions was assessed byhand-shaking using an arbitrary scale A to E (good to bad). The resultsare given in Table 5 below under the column headed TR92.

The titanium dioxide millings were repeated except using Dispersant(0.25 parts), 4:1 mixture of methoxypropylacetate/n-butanol (6.75 parts)and a red iron oxide pigment (3 parts, Sicotrans Red L2817 ex BASF). Thefluidity of the resultant dispersions is also recorded in Table 5 underthe column headed L2817.

TABLE 5 Example Dispersant TR92 Fluidity L2817 Fluidity 29 1 A A/B 30 2A B/C 31 3 A B/C 32 5 A C 33 6 A C 34 7 B B 35 8 A/B B/C 36 9 A C 37 10A B/C 38 11 A/B B 39 12 A B 40 13 B C 41 14 B B/C 42 15 A A P A A A Q BB C R D B B S E B B T F B C U G A A V H C C W I C C Control 1 B B/CControl 2 E D Footnote to Table 5 Control 1 is the phosphate ester ofε-caprolactone polymerised in the presence of lauryl alcohol. Control 2contains no dispersant and where the amount of dispersant is replaced bythe same amount of solvent.

What is claimed is:
 1. A dispersant which is a phosphate ester of aTPOAC alcohol of formula 1 RO(CO—A—O)_(n)(CO—B—O)_(m)H  (1) includingsalts thereof wherein R is a polymerization terminating group containingat least one ether link; A and B are each, independently, differentalkenylene groups or C₁₋₁₇-alkylene groups optionally substituted byalkyl; n and m are positive integers; and n+m is from 2 to
 200. 2. Adispersant as claimed in claim 1 wherein R is the residue of amonohydroxyglycol or a monohydroxypolyalkyleneglycol.
 3. A dispersant asclaimed in claim 2 wherein the glycol or polyalkyleneglycol is derivablefrom ethylene oxide and/or propylene oxide.
 4. A dispersant as claimedin either claim 2 or claim 3 wherein the glycol or polyalkyleneglycol isderivable from ethylene oxide.
 5. A dispersant as claimed in claim 1wherein R is a residue of a hydroxy compound T—OH which is attached to amonohydroxyglycol or a monohydroxypolyalkyleneglycol.
 6. A dispersant asclaimed in claim 5 wherein T is C₁₋₃₅-hydrocarbyl optionally substitutedby halogen, tertiary amino, hydroxy or C₁₋₆-alkoxy.
 7. A dispersant asclaimed in claim 5 wherein T is C₁₋₆-alkyl.
 8. A dispersant as claimedin claim 5 wherein T is methyl.
 9. A dispersant as claimed in claim 1wherein R is the residue of tripropyleneglycolmonomethylether,triethyleneglycolmonomethylether, methoxyethyleneglycols, andmethoxypropyleneglycols having a molecular weight between 250 and 750.10. A dispersant as claimed in claim 1 wherein A and B are bothC₁₋₆-alkylene optionally substituted by alkyl.
 11. A dispersant asclaimed in claim 1 wherein A and B are derivable from δ-valerolactoneand ε-caprolactone optionally substituted by C₁₋₆-alkyl.
 12. Adispersant as claimed in claim 1 wherein one of A and B is derivablefrom δ-valerolactone and the other is derivable from ε-caprolactone. 13.A dispersant as claimed in claim 1 wherein the molecular weight of theether moiety is greater than that of the POAC chain.
 14. A dispersant asclaimed in claim 1 wherein the ratio of the TPOAC alcohol to phosphorusatom is between 3:1 and 1:1.
 15. A process for making a dispersant asclaimed in claim 1 which comprises reacting two differenthydroxycarboxylic acids or lactones thereof in the presence of apolymerisation terminating compound in an inert atmosphere at atemperature between 150 and 180° C. to form a TPOAC alcohol and reactingthe TPOAC alcohol with a phosphating agent.
 16. A composition comprisinga particulate solid and a dispersing agent as claimed in claim
 1. 17. Adispersion comprising a dispersant as claimed in claim 1, a particulatesolid and a liquid medium.
 18. A dispersion as claimed in claim 17wherein the liquid medium is a polar organic liquid or water.
 19. Amillbase comprising a dispersant as claimed in claim 1, a particulatesolid, a liquid medium and a film-forming resin.
 20. A paint or inkcomprising a dispersant as claimed in claim 1.